The article presents a case of chronic odontogenic maxillary sinusitis and the results of its surgical treatment. The cause of the sinusitis, confirmed by the results of X-ray and pathohistological studies, was an inflammatory process affecting the bone tissue around the implant, installed in the place of the upper first molar which was accompanied by the development of an oroantral fistula. During the surgical intervention, the communication between the oral cavity and the maxillary sinus was eliminated, and the implant with the abutment, which was entirely in its cavity, was also removed.